1. Field of the Invention
The invention relates the field of treating hot rolled stainless strip and strip cast and, more particularly, to a method for converting hot rolled stainless steel strip and strip cast to a final gauge product in a continuous operation.
2. Description of the Background Art
The most widely used procedure for converting hot rolled or strip cast stainless steel (hot band) into a final gauge cold rolled product consists of converting the hot band to an annealed, shot blasted, and pickled "white band" and subsequently cold rolling that product to final gauge. Extensive cold rolling of the strip is necessary to produce a smooth surface. This extensive cold rolling is necessary because shot blasting and other surface cleaning steps are used to crack and remove the scale that forms on the surface of the stainless steel strip during hot rolling and strip casting. The cold rolling step is also necessary to bring the thickness of the hot band and strip cast strip to within cold-rolled tolerances even when the hot band or strip cast band can be produced to a gauge normally obtained by cold rolling.
U.S. Pat. No. 5,197,179 is representative of the typical procedure for forming a final gauge product from hot band. Therein, the hot band is converted to a cold rolled product by cold rolling, annealing and pickling. However, the cold rolled product formed by that process has a shot-blasted finish and thus is in a condition requiring subsequent processing to final gauge. It is not itself in a final gauge condition. Rather, the cold rolled product must still be subsequently rolled to final gauge.
The extensive cold rolling required by the prior processes limits the ability of the hot band to be converted into a final gauge product in a single, continuous operation. This adds both time and cost to the final gauge production. Accordingly, there is a need for a continuous process for converting hot band and strip cast into final gauge product which does not require extensive cold rolling of the stainless steel.